1. Field of the Invention
The present invention relates to devices installed within oil and gas well pipe for conducting well bore operations and, specifically, to an equipment insert which is installed within a section of well pipe at the surface and which is then made up into a pipe string and run into the well bore.
2. Description of the Prior Art
In this specification, the term "pipe" will be understood to refer to well pipe, tubing, casing, etc. The term "equipment" will be understood to mean devices of the type used in conducting well bore operations including landing collar inserts, flapper valves, back pressure check valves, ball catching subs, baffle type catcher subs, valve type orifice float collars, orifice float collars, cementing bridge plugs, cementing retainers, cementing set shoes, plugs in flow lines and similar equipment.
In the past, the required well bore equipment was typically provided in a specialized pipe sub which would be made up into the pipe string of the customer. This was problematical, at times, because some customers utilized pipe strings with custom threads which would not match the threads of the specialized pipe sub, or which would require cutting special threads on the specialized sub.
U.S. Pat. No. 4,248,300, entitled "Method of and Apparatus for Positioning Retrievable Landing Nipple in a Well Bore String", issued Feb. 3, 1981, is typical of prior art devices in which a landing collar is run into the well bore on a pipe string and secured within a surrounding well conduit. The landing collar is latched into a specially milled groove in the surrounding conduit. U.S. Pat. No. 4,399,873, entitled "Retrievable Insert Landing Assembly", issued Aug. 23, 1983, shows another landing assembly which is run into the interior bore of a packer and which is engaged to provide a landing shoulder within the packer by latching the device within a groove milled within the bore of the packer. Such prior art devices suffer from the deficiency of requiring special milling of the surrounding conduit or special couplings and threads in the surrounding conduit.